May 30, 1889] 



NATURE 



10^ 



THE u^OOLOGICAL S OCTET YS INSECT 

 HOUSE. 



ALTHOUGH it has long been the practice of ento- 

 mologists to keep private collections of the larva2 of 

 insects, for the purpose of studying their metamorphoses 

 and of obtaining perfect specimens of their fully-deve- 

 loped forms, there is, we believe, still only one place 

 where the attempt is made to attract public attention to 

 this most varied and wonderful group of animals by an 

 exhibition of them and of the different stages of their life- 

 history. This place is the Insect House of the Zoological 

 Society of London in the Regent's Park Gardens, which 

 has now been maintained with considerable success for 

 several years. 



At this season of the year the Insect House is gene- 

 rally at its best, and examples of the perfect insect are 

 continually to be seen emerging from the chrysalis. 



Leaf-insect of the Seychelles {Phyllium gelonns). 



A very interesting and novel addition has just been 

 made to the collection in the form of a specimen of one 

 of the Leaf-insects, presented by Lord Walsingham, who 

 received it from the Seychelles Islands through Colonel 

 Larking. Though not yet fully developed, there can be 

 no doubt it will prove to be an example of Phylliuni 

 gelonus. Gray. The insects of this remarkable genus 

 are all Oriental, inhabiting the tropical regions of 

 Asia, and extending to Mauritius and the Seychelles. 

 It has hitherto proved impossible to induce them to 

 continue their species in this country beyond a single 

 generation, so that it is only occasionally that they 

 can be seen alive here. So long ago as 1854 a 

 living specimen of an Indian species, P. scythe, was 

 exhibited in the Botanic Gardens at Edinburgh, where it 

 attracted so much attention that it was found necessary 

 to limit its exhibition to four days in each week. This 

 restriction was (as stated by Murray) adopted because, in 



spite of the old saying that seeing is believing, it was 

 found in the case of this insect that seeing was disbeliev- 

 ing. On those who inspected it insisting that there was 

 no insect on the plant, but only a leaf, it had to be 

 stirred up to convince them of the truth, and this pro- 

 cess of continual provocation was found to be very 

 injurious to the constitution of so peaceable a creature. 



The resemblance of many of the species of this group 

 of Orthoptera to portions of the plants on which they are 

 found is so extreme that it has given rise to a firm con- 

 viction in the minds of the inhabitants of some of the 

 regions in which they are found that they are portions of 

 the actual plant transformed into living insects. There 

 is certainly more to be said for the belief in this 

 metamorphosis than there is for some of the transforma- 

 tions related by Ovid ; and M. de Borre, in the Comptes 

 retidus of the Belgian Entomological Society (1883), has 

 explained the reasoning by which it is justified. The 

 people having observed the gradual growth of the creature 

 and the development of the appendages of the body, while 

 they have failed to see it when very small and issuing 

 from the ^'g'g, maintain stoutly that a young leaf gradually 

 grows into a living insect. The species of the genus 

 Phylliiun all have a remarkable resemblance to leaves, 

 but it appears as yet not to be known whether the 

 different species have a special resemblance to the foliage 

 on which they feed. 



The late Andrew Murray published an account of the 

 Edinburgh specimen in the Editiburgh New Philosophical 

 Journal for 1856, and then said that he " should not be at 

 all surprised if, in the course of a few years, the Leaf- 

 insect should be as common an inmate of our conser- 

 vatories as the canary-bird now is of our dwellings." This 

 hope has, however, not been realized, and for our oppor- 

 tunities of seeing it in the living state we are obliged 

 still to rely on (he kindness of naturalists who may be 

 stationed in the tropical regions where these creatures 

 exist, and who will take the trouble of bringing or send- 

 ing them or their eggs over to us. The difference 

 between a living and a dead insect is not so extreme as 

 that between a live dog and a dead dog, but still it is 

 very great, and one of our older entomologists used to 

 say that he never really knew the species of an insect till 

 he had seen it alive. 



The Insect House in the Zoological Gardens affords, as 

 we have said, the only opportunity that the English public 

 have of seeing alive some of the wonderful forms of 

 tropical insects. But, as we have already remarked, the 

 difficulty of perpetuating the hfe of these examples of 

 exotic Nature's variety and luxury beyond a short period is 

 excessive, and reaches its maximum in London. There 

 is, perhaps, nothing more remarkable in Nature than the 

 pertinacity and rapidity with which the generations of 

 many of the lower forms of insect life are produced. 

 Phylloxera, Aphis, scale-insects almost defy the efforts of 

 mankind to control them, and the resources of even 

 scientific civilization contend with them as yet almost in 

 vain. But in many of the more evoluted forms of insects 

 we find a very different condition prevalent. Even 

 mating can, in a large number of cases, be induced only 

 when the creatures are placed in exactly appropriate cir- 

 cumstances, and afterwards the insects will only deposit 

 their eggs in such places and under such conditions as 

 insure at least a probability of congenial existence for their 

 progeny. In the case of many species the females prefer 

 to die with their eggs undeposited, rather than place them 

 in conditions that are at all inappropriate. Thus the 

 difficulty of keeping up a varied supply of curious forms 

 for the Insect House is very great. 



The different kinds of silk-producing moths have at- 

 tracted much attention for a considerable number of years 

 past, and in the case of several species fertile eggs are 

 readily procured. These insects, being in many cases 

 very large and attractive creatures, excite a good deal of 



